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Rapid testing identifies antibody efficacy against COVID-19 variants

A new test can quickly test the ability of antibodies to neutralize peak proteins from different variants of COVID-19 simultaneously. The D4 analysis shown here is the Teflon-like technology that makes the test possible. Credit: Duke University

Biomedical engineers at Duke University have devised a test to quickly and easily assess how well a person’s neutralizing antibodies fight infection from several variants of COVID-19 such as Delta and the newly discovered Omicron variant.

This test could potentially tell physicians how protected a patient is against new variants and those currently circulating in a community, or vice versa, which monoclonal antibodies should treat a COVID-19 patient. The test is described online on December 3 in the journal The progress of science.

“We currently have really no quick way to assess variants, neither their presence in an individual, nor the ability of antibodies we possess to make a difference,” said Cameron Wolfe, associate professor of medicine at Duke University School of Medicine. “It is one of the persistent fears that as we successfully vaccinate more and more people, a variant may emerge that more radically evades vaccine-induced antibody neutralization. And if that fear came true – if Omicron showed to be a worst-case scenario – how should we know it fast enough?

“While developing a point-of-care test for COVID-19 antibodies and biomarkers, we realized that there could be an advantage in being able to demonstrate the ability of antibodies to neutralize specific variants, so we built a test around that idea. , “said Ashutosh Chilkoti, Alan L. Kaganov Distinguished Professor and Chair of Biomedical Engineering at Duke. “It only took us a week or two to incorporate the Delta variant into our test, and it could easily be extended to include the Omicron variant. All we need is the tip protein from this variant, which many groups around the world – including our group at Duke – is working feverishly to produce. “

The researchers named their test COVID-19 Variant Spike-ACE2-Competitive Antibody Neutralization assay, or CoVariant-SCAN for short. The technology of the test depends on a polymeric brush coating that acts as a kind of non-stick coating to prevent anything other than the desired biomarkers from adhering to the test tube when wet. The high efficiency of this non-stick shield makes the test incredibly sensitive to even low levels of its target. The approach allows researchers to print different molecular traps in different areas of the slide to capture multiple biomarkers at once.

In this application, researchers are printing fluorescent human ACE2 proteins – the cellular targets of the virus’ infamous nail protein – onto a slide. They also print peak proteins specific for each variant of COVID-19 at different specific sites. When the test is run, the ACE2 proteins detach from the slide and are captured by the tip proteins that are still attached to the slide, causing the slide to glow.

However, in the presence of neutralizing antibodies, the tip proteins are no longer able to grip the ACE2 proteins, causing the slide to glow less, indicating the effectiveness of the antibodies. By printing different variants of the COVID-19 tip protein on different parts of the slide, the researchers can see how effective the antibodies are at preventing each variant from sticking to their human cellular targets at the same time.

In the paper, the researchers tested the technology in a number of different ways. They tested monoclonal antibodies, either from real patients or from Regeneron’s commercial prophylactic treatment. They also tested plasma taken from healthy vaccinated people and those currently infected with the virus.

Rapid testing identifies antibody efficacy against COVID-19 variants

The new test of how well antibodies work against multiple variants of COVID-19 works by releasing fluorescently labeled ACE2 proteins – the cellular targets of the COVID-19 peak protein – along with antibodies. If the antibodies are able to neutralize variants of COVID-19 spike proteins printed on the slide, they cannot bind to the ACE2 proteins, causing the fluorescent markers to wash away and the slide to become weaker. Credit: Jake Heggestad, Duke University

“In all of our tests, the results largely mimicked what we’ve seen in the literature,” said Jake Heggestad, a Ph.D. students working in the Chilkoti Laboratory. “And in this case, it’s a good sign not to find anything new, because it means our test works just as well as the methods currently in use.”

Although they produce similar results, the critical difference between CoVariant-SCAN and current methods is the speed and ease with which it can produce results. Typical current approaches require isolation of live viruses and cell culture, which can take 24 hours or more and require a wide range of security measures and specially trained technicians. CoVariant-SCAN, on the other hand, does not require live viruses, is easy to use in most settings, and takes less than an hour – potentially only 15 minutes – to produce accurate results.

Going forward, Heggestad and the Chilkoti Laboratory are working to streamline the technology into a mass-produced microfluidic chip and report results with just a few drops of blood, plasma or other liquid sample containing antibodies. This approach has already been shown to work on a similar test that can distinguish COVID-19 from other coronaviruses.

“We would love to have real-time visibility of the new variants and understand who still has functional immunity,” Wolfe said. “In addition, this suggests that there may be a technique by which one can quickly assess which synthetic monoclonal antibody might be best to administer to a patient with a particular emergent variant. At present, we really have no real-time way of knowing so we rely on epidemiological data that can track weeks afterwards. “

“The reverse is also true,” Wolfe continued. “To be able to pre-screen an individual’s antibodies and predict whether they were adequately protected against a particular variant they may be running into while traveling, or which appear in their territory. We have none. way to do at the moment time. But a test like CoVariant-SCAN could make all these scenarios possible. ”

Regeneron says COVID antibody therapy may be less effective against Omicron

More information:
Jacob Heggestad et al., Rapid test to assess the escape of SARS-CoV-2 variants of concern, The progress of science (2021). DOI: 10.1126 / sciadv.abl7682.

Provided by Duke University

Citation: Rapid Test Identifies Antibody Effectiveness Against COVID-19 Variants (2021, December 3) Retrieved December 5, 2021 from

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